Phonograph pick-up mechanism



July 31, 1934- w. H. HUTTER PHONOGRAPH PICK-UP MECHANISM Filed Aug. l?,1951 FIEI.

PIEI ATTORNEYS.

Patented July 31,1934

- narran; STATES ortica.

Y. 1.968.149l y I PHQNOGRAPHl PIoK-UrMECiiANI'sM. William H. Hutter,Fort Wayne, Ind., assignorto The Capehart Corporation, k-Fort WaynefInd.. a

' a corporation.

Application August 17. 1931'.` serialv 'traiga 6 Claims."V (Cl.179-100.41)

I I his invention relates to phonograph pick-'up mechanism. Theprincipal object of theinven tion is to provide such mechanism in whichextraneous noises are reduced as muchas possible. Another object of theinvention is toprovide an electromagnetic type of pick-up vin which thevibrationof Vthe stylus has a-maximuin electrical effect .upon theinduced current in thepick-up COll. y

A further object of the invention is to so form the parts that pick-uptalk is greatly reduced.

Still another object of the invention is to provide such-mechanism inwhich the magnetic pole pieces land pickfup coil may be placed in ahorizontal position while the stylus is inclined at an angle to thehorizontal. y One feature of the invention by which the extraneous noiseisreduced residesv inthe provision of a pivotal and resilientmountingrfor the sound box upon the outer end of `vthe pick-up arm. Bythis means, transmission of gear and motor vibrations fromthe phonographto the pick-up mechanism contained in the soundybox issubstantiallyminimized. 2 p o; Another feature of the invention by whichthe electrical effect of the stylus movementgisincreased resides in. theYprovisiollf additional weight in the sound box. itself to increase Vtheinertia thereof and lbalance the same on .the 3o stylus. VBy this means,vmovement of the` sound box itself, in response tomovements of thestylus, is practically prevented l,so that the relative movement of thestylus and the magnetic parts carried 'by thesound box is greatlyincreased; The effect of this feature is increased by the.

combination of the added Weight vwith there-"k silient mounting of thesound box. y'

The electrical sensitivity is increasedby the ofthe magnetized polepieces cooperating therewith. A large proportion of the magnetic. flux*Small ,movements Lof thev `brations which result in anappreciablesoundin the vsound box itself.1 This sound'is known aSYpiCk-up talk and .i'saudiblewhentheamplication mechanism ofgjthephonograph is dise;connected.Vv When the armature is round or stream-lined in form, as inthepresent invention', these air vibrations are minimized. l Otherobjects and features; of .the invention will be apparent from Vtheaccompanying drawing andthe followingy description and claims:

Figure' 1. is a plan viewpartly inv .section of the sound box attachedto the end'of the pick-up arm and illustrates the pivotal and resilientmounting ythereoLf lFigure, v2 isvv an elevational y view-.of ythe sameVpartly in'sectionillustrating 70 particularlytheV `mechanism forYcleaning the record.- Figure 3. is` aplan View of the sound box.withthe'cover. removed. VFigure 4 vis a sectional l. viewtaken substantiallyvo'n'the 'line -e of Figure .1'. Figure 5 is `anend vview of 75thezsound boxwith thejcoverremoved.- Figure 6.7.isfa perspective.view4of therarmature and of theitop of the. said`.armature in onefformand Figure 8 is a similar-"viewof an alternative B0 form thereof.

I '.fi f

In therdrawing-,the outer end of theVpick-#up arm of a phonograph isindicated bythe numeral 101 The said pick-up arm J-is fof v a forkedconstruction, best shown in iFigure .-1, havingarms '85 11 by whichthere Vis xedly-carried a substantially horizontal pivot pin-12;`YThefsaid pivot` pin is maintained inlplace bya s et screvv 13. Ateachnendof .thepivot pini-12 adjacent the Iarms 11, thereis'provided'afbushing 14 of rubber or 90 other resilient material. 'yThe said bushings are engagedin suitable-openingsin a cover 15' of thesoundrboxi vThe saidrcoverfis thereby pivotally andA resilientlyAymounted upon the pivot. u pir1'12.V Y J' 95 The sound box'isprovided'vvith a base member 16 having an upwardly-extending centrallugl'l and a pair of lugs 1 8 positioned ne'ar'the corners of the front'edge. yScrews 19- pass-'through ysuitable openings inf the vcover 15a'nd are" 10,0

threadedly engaged-witlithe -lugsf 1'7 and 18f to v support the 4basemember l and pa'rts carl' ried thereby. As will be seen particularly inFigure 3, the lugs 18 are much larger than neces- Qs sary to accommodatethe screws 19. thus serve to increase the inertia of the forward part ofthe base member 16 for the purpose hereinbefore described. It Will alsobe seen, with particular reference to Figures 2 and 4, that the @dforward end 20 of the base member is made con- 11% The lugs lOrsiderably thicker than the rearward end 21 thereof. The increasedthickness of the forward end also contributes to the increase of inertiaof that part of the sound box adjacent the movable armature hereinafterparticularly pointed out.

Adjacent the front edge of the sound box and mounted upon the basemember 16 by means of screws `22 there are a pair of pole pieces 23 eachhaving an upper portion 24 and alower portion 25. The said pole piecesare magnetized by a horseshoe magnet 26 abutting against the same.Between the upper and lower portions of 'the pole pieces 23 there ispositioned a pick-up coil 27 mounted upon a spool 28) vIn thecenter ofthe spool 28 there is provided a bushing 2 9 of rubber or otherresilient material and the said bushing resiliently holds the upper endof an armature 30. The upper and lower surfaces of the spool 28 areprovided with slotted'grooves 31 in which the upper and lower portions`of the pole pieces 20 are engaged. The said spool may, therefore', beslidably moved with respect to the said pole pieces to` adjust therelative position of the pole pieces 'and'armature Whencthe properposition is obtained, the spool is fastened in place i by means of setscrews 32'. The pick-up coil 27 is connected by electrical leads 33 toterminals 34 carried by a terminal block 35 mountedat the rear edge ofthe sound box. Terminals 34"' have attached thereto leads 36 passingupwardly and through the pick-up arm and connected to suitablelamplification apparatus.

l Thefarmature Sil-consists of an upper portion 37 substantiallycylindrical in form and extending," asbest shown in Figure 4, to a levelslightly below the upper level of the upper portion of the pole pieces23. Beneath the portion 37 of the armature there is'formed aVrectangular portion 38 carrying cylindrical arms 39 which aresurroundedV byresilient bushings 40 and clamped between the lowerportions Y25 of the pole pieces 23." Bene'athvthe rectangular portion 38thereis providediaportion 41-A extending downwardlyi at an-acute angle`to thejhorizontal and the said I portionf41 is provided with a suitableopening for the reception ofca stylus 42.- The said stylus is clamped inplace by means of a screw43 engaging `af-suitabl'eV threadedopening 'in'Vone 'of the arms-39. 1?ythis construction of the armature, it -will Vbeseen that @the upper "surface" has'a substantial-area forr thereception-of magnetic flux of the' armature and-pole piecesythe Vchangeof flux due to movement of the stylus 'and armature is much greaterthan-withtypes of armature previously used It will also' be seen thatthe cylindrical portion -37 ywill causefmuch less V'disturbance of theair surrounding the same and,

therefore, reduceslfpick-up talk. YThis effect' is even-morepronounced-'whenthe upper portion of the-armature is formed with astreami line cross'section as shownwat 137 lin Figure 8. It

will also be'seen that the provision-of theV inclined portionV 41permits the stylus to project` at the proper.angle to engage the recordwhile the pole pieces and pick-up coil are in a substantially horizontalplane. The sound box as a whole, therefore, occupies much less space ina vertical direction.

For cleaning a record as it is played and drawing the stylus into thegroove, there is provided a brush 44 mounted on the end of an arm 45which is pivotally carried upon a lug 46 formed upon the base member 16and which projects downwardly through an opening 47 in the said basemember. The said arm is engaged by one end of a tension spring 48, theopposite end of which is fastened to an ear 49 formed on the base member16'. The said spring, therefore, serves tokeep the brush 44.in contactwith the record independently of the length of stylus employed.

'Ihe invention claimed is:

1. Phonograph mechanism having a pick-up arm, and an induction typesound box, characterizedv by weights carried by said sound box toincrease the inertia and balance thereof, and a pivotal, resilientmounting for supporting said sound box upon said arm. s

2. A phonograph sound' box having a base portion, electromagneticpick-up mechanism 1 supported on said base, a resiliently-mounted iarmature and a stylus carried by said armature, characterized by meansfor pivotally and resiliently mounting said sound box upon the piel;- uparm of a phonograph, and by weighted lugs 1 formed on said base portionto increase the iner- J?- tia and balance thereof.

3. Phonograph pick-up mechanism having a pair of magnetized pole pieceseach having an upper and a lower portion, a'pick-up Vcoil spool 1mounted between the upper and lower portions of said pole pieces, and anarmature mounted in the center of said spool, characterized by saidspool being slidably mounted for adjustment on lsaid pole pieces.

4. Phonograph pick-up mechanism having a pair of magnetized pole pieceseach having an upper anda lower portion, a pick-upfcoil spool mountedbetween the upper and lower portions of said pole pieces, and anarmature mounted in the center of said spool, characterized bythesurface of said spool having a slotted recess engaged by said polepieces for slidingadjustrnent.

' 5. Phonograph pick-up mechanism having a pair of magnetized polepieces each having an upper and a lower portion, a pick-up coil spoolmounted between the upper and lower portions of said pole pieces, and anarmature mounted in the center of said spool, characterized by the upperand lower surfaces of said spool having l slotted recesses thereinengaged by said pole pieces for sliding adjustment.

6. A phonograph sound box having an electromagnetic pick-up mechanism, ahousing' enclosing said pick-upA mechanism, said housing being .l

formed with forwardly and laterally flared side .Y

wallssubstantially spaced from said mechanism lto provide compartmentsc'n each side thereof,

WILLIAM H. HUTTER.V

